1. Field of the Invention
The present invention relates generally to an apparatus and method for measuring a dose in an injector, and more particularly, to an apparatus and method for measuring a dose in an injector, which is capable of measuring a dose without modifying the mechanical structure of the injector.
2. Description of the Related Art
A type 1 diabetic patient's body does not produce enough insulin that is essential to survival, so he or she needs to continuously measure a blood glucose level and inject an appropriate dose of insulin. Currently, an insulin pen that conveniently allows a user to personally inject insulin has been distributed on the markets. The insulin pen is designed to determine a specific dose by turning a dose-marked knob, and inject insulin by pressing a button disposed at the end of the insulin pen.
A patient records information about when and how much insulin is injected, and his or her medical attendant checks the recorded information to determine whether a patient's disease state is controlled, thereby increasing the effect of treatment.
However, for an insulin pen which allows an individual to adjust and inject a specific dose of insulin personally according to an aperiodically checked glucose level, as well as a complicated system like an insulin pump which measures a glucose level for twenty-four hours in real time and continuously injects a slight dose of insulin, there are no inexpensive methods for checking when and how much insulin is injected and transmitting the checked information.
To conventionally measure a dose of insulin, an amount of insulin in a syringe containing an injection liquid or a position of a syringe piston is measured. For an insulin pump similar to an insulin pen, the number of revolutions of a motor and a screw for moving a syringe piston is measured.
However, the above-mentioned techniques are difficult to apply to the structures of insulin pens that are available on the markets.
With a currently used insulin pen, a user determines a dose by turning a number sleeve of the insulin pen and, when the user presses a button disposed at the end of the insulin pen, a screw provided in the number sleeve is connected to a clutch and performs a spiral movement to move a piston forward within in an insulin injector. In other words, a screw nut is not moved during a rotary movement of the screw, and the screw moves forward while performing a spiral movement. When the screw performs only a rotary movement, it is easy to measure the number of revolutions corresponding to a spiral movement distance. However, when the screw directly moves forward while performing a spiral movement, it is difficult to measure the number of revolutions of the screw.
Moreover, when a dose is measured using a capacitance/inductance/optical mark, a measuring apparatus is disposed at the front of a syringe, which will increase a size thereof Also, manufacturing costs increase due to the addition of a physical quantity measuring apparatus to a disposable syringe.